Liquid fuel injection pumping apparatus

ABSTRACT

A FUEL PUMP FOR SUPPLYING FUEL TO AN INTERAL COMBUSTION ENGINE AND INCLUDING AN INJECTION PUMP, WHICH DELIVERS FUEL TO THE ENGINE DURING THE INJECTION STROKES THEREOF, AND TO WHICH FUEL IS DELIVERED DURING THE FILLING STROKES THEREOF BY WAY OF A NON-RETURN VALVE FROM A SOURCE OF FUEL UNDER PRESSURE, THE NON-RETURN VALVE INCLUDING A VALVE ELEMENT WHICH IS DISPLACED FROM ITS SEAT TO PERMIT FUEL TO FLOW TO THE INJECTION PUMP AND A PISTON MEMBER WHICH IS URGE TOWARDS THE VALVE ELEMENT BY FUEL UNDER PRESSURE FROM THE SOURCE. THE PISTON ACTS TO CLOSE THE VALVE ELEMENT QUICKLY AS THE FLOW OF FUEL TOWARDS THE INJECTION PUMP CEASES.

May 23, 1972 M. DRORI 3,664,773

LIQUID FUEL INJECTION PUMPING APPARATUS Filed Sept. 4., 1970 2 Sheets-Sheet l INVENTOR TTORNEYS Mym May 23, 1972 M. DRORI LIQUID FUEL INJECTION PUMPING APPARATUS 2 Sheets-Sheet 2 Filed Sept.

INVENTOR //fl4 9940a ATTORNEYS United States Patent U.S. Cl. 417-507 5 Claims ABSTRACT OF THE DISCLOSURE A fuel pump for supplying fuel to an internal combustion engine and including an injection pump, which delivers fuel to the engine during the injection strokes thereof, and to which fuel is delivered during the filling strokes thereof by way of a non-return valve from a source of fuel under pressure, the non-return valve including a valve element which is displaced from its seat to permit fuel to flow to the injection pump and a piston member which is urged towards the valve element by fuel under pressure from the source. The piston acts to close the valve element quickly as the flow of fuel towards the injection pump ceases.

This invention relates to liquid fuel injection pumping apparatus of the kind comprising in combination, an injection pump which in use, is actuated in timed relationship with an associated engine and which during an rn ection stroke delivers fuel under pressure to the engine, a shuttle slidable in a bore, stops at the opposite end of the bore to limit the excursion of the shuttle and means for feeding fuel during successive filling strokes of the injection pump, from the opposite ends of the bore in turn by causing displacement of the shuttle therein.

With such apparatus it has been found that with increasing speed the quantity of fuel delivered by the apparatus deviates considerably from the geometric displacement of the shuttle and this is attributed to the fact that the quantity of fuel which is fed to the injection pump varies with speed. Investigation of this problem has led to the conclusion that the velocity gained by the fuel during its passage to the injection pump is the reason for the variation in output. When the shuttle is partaking of its maximum excursion it is halted suddenly by the stop at the appropriate end of the bore. However, the fuel intermediate the end of the bore and the injection pump cannot be brought to rest'immediately and because of its velocity it tends to continue flowing into the injection pump. The effect of this is that a larger quantity of fuel is supplied to the injection pump than the expected amount and a cavity is formed somewhere intermediate the injection pump and the end of the bore. The cavity is filled during the next cycle but the extra fuel which has entered the injection pump is delivered at the next injection stroke so that the delivered volume of fuel is above the expected value. I The object of the present invention is to minimise the flow of such extra fuel into the injection pump.

According to the invention in a pumping apparatus of the kind specified there is provided in a conduit leading to the injection pump and through which fuel flows from the bore containing the shuttle to the injection pump, a one'way valve including a valve element which is displaced from a seating by the fuel flowing along said conduit to the injection pump and a fluid pressure operable member which acts on the valve element in a direction to urge it onto the seating, the force applied by said member being sufficient to minimise the flow of fuel into the injection pump after the shuttle has contacted the stop.

One example of a liquid fuel pumping apparatus in ac- "ice cordance with the invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a sectional side elevation of the apparatus with parts removed for the sake of simplicity, and

FIG. 2 is a section on the line A-A of FIG. 1 and looking in the direction of the arrows.

Referring to the drawings there is provided a body part 10 in which is formed a cylindrical bore 11 which accommodates a rotary cylindrical distributor member 12. At one end of the distributor member there is provided a transversely extending bore 13 in which is mounted a pair of reciprocable pumping plungers 14. The plungers are arranged to be moved inwardly through the intermediary of rollers 9, by the action of pairs of cam lobes formed on the internal periphery of an annular cam ring 8 which surrounds the distributor member at this point. The distributor member is arranged to be driven in timed relationship with an associated engine which in the present example is provided with six cylinders. Located at the opposite end of the distributor member is the rotary part of a feed pump shown diagrammatically at 7 which has an outlet connected to a supply passage 15 formed in the body part 10. The feed pump is provided with an inlet 6 which is connected to a source of liquid fuel and the inlet and outlet are interconnected by a relief valve 5 which controls the output pressure of the feed pump so that it varies in accordance with the speed at Which the apparatus is operating.

The transversely extending bore 13 is in communication with a longitudinal passage 16 which at its end remote from the bore 13 communicates with an outwardly extending delivery passage 17. This passage is arranged to register in turn and as the distributor member rotates, with six equiangularly spaced outlet ports 18 formed in the body part, and which communicate respectively with the injection nozzles of the associated engine. The communication of the passage 17 with a port 18 takes place during the time when the plungers 14 are being moved inwardly by the action of the cam lobes and in this manner fuel contained in the bore 13 will be displaced to the associated engine. The bore 16 intersects an obliquely disposed bore 19 which contains a one way valve (to be described more fully below) but this valve remains closed whilst fuel is being delivered to the associated engine.

The supply passage 15 communicates with one end of a cylindrical bore 20 formed in the body part, this communication being achieved by a circumferential groove formed on the periphery of the distributor member. The bore 20 contains an angularly adjustable throttle member 7a and by which the quantity of fuel which can flow through a passage 21 to a circumferential groove 22 formed on the distributor member, can be controlled. The circumferential groove 22 communicates with three equiangularly spaced and axially extending grooves 23- formed in the periphery of the distributor member and these grooves are positioned for registration with a pair of circumferentially spaced ports 24, 25 formed in the body part and opening out onto the periphery of the distributor member.

The distributor member is provided with a further circumferential groove 26 which communicates with the longitudinal passage 16 by way of the one way valve generally referenced 27 and extending from the groove 26 are three longitudinal grooves 28. The grooves 28 are equiangularly spaced and are disposed alternately with the grooves 23. The circumferential spacing of the ports 24 and 25 is such that when a groove 23 is in register with the port 24 a groove 28 will be in register with a port 25 and vice versa.

The ports 24 and 25 communicate with the opposite ends respectively of a bore 29 formed in the body part. Axially slidable within the bore 29 is a shuttle 30 and stops 31, 32 are provided at the opposite ends of the bore to limit the excursion of the shuttle. As is shown, the stop 32 is adjustable so that the maximum excursion of the shuttle can be determined. It will be noted that the axis of the bore 29 is at right angles to the axis of rotation of the distributor member and that the length of the ports 24 and 25 is substantially equal.

The operation of the apparatus thus far described is as follows. As shown in the drawings, an injection stroke has just taken place and the delivery passage 17 is now out of communication with an outlet 18. Moreover, groove 23 is in communication with port 24. In this condition fuel can flow from the inlet passage by way of the metering member, the circumferential groove 22 and the groove 23 to the end of the bore 29 which is associated with the port 24. This flow of fuel causes movement of the shuttle 30 towards the left as viewed in FIG. 2. Fuel contained in the end of the bore associated with the port 25 flows through this port and by way of the grooves 28 and 26 and the non-return valve 27, to the longitudinal bore 16 and the bore 13. The flow of fuel causes outward movement of the pumping plungers 14 which in association with the cam lobes constitute the injection pump. This flow of fuel, assuming that the throttle member 7a is set to provide the maximum flow, continues until the shuttle strikes the stop 32. During continued movement of the distributor member the ports 24 and 25 are isolated from the grooves 23, 28 and the delivery passage 17 moves into communication with an outlet 18. At this point the pumping plungers 14 are moved inwardly and a fresh supply of fuel is delivered to the engine. At the next filling stroke of the injection pump the port 24 is brought into register with a groove 28 and the port 25 in register With a groove 23. The effect of this is that the shuttle 30 is moved in the opposite direction into contact with the stop 31.

As explained in the opening of the specification it ha been found that with increasing speed the quantity of fuel which enters the injection pump is larger than the theoretical quantity due to the displacement of the shuttle 30 and it is to minimise the flow of extra fuel that the oneway valve 27 is provided. The one-way valve is described and claimed in the specification of United States Patent application No. 864,505. The valve comprises a pair of body portions 33, 34 which are screw threadedly engaged within the opposite ends of the bore 19. The portion 34 is hollowed out to define a cavity in which is located a valve element in the form of a ball 35 and at one end of the cavity is a seating for the ball. This end of the cavity communicates with the circumferential groove 26 and the opposite end of the cavity effects communication between the parts of the passage 16. During an injection stroke of the pump the ball is urged into contact with the seating to prevent flow of the fuel from the passage 16 to the circumferential groove 26. Formed in the member 33 is a cylindrical bore which at its outer end communicates with the supply passage 15. In the bore is mounted a slidable cylindrical member 36 which at its end within the cavity, is provided with a head 37 which co-operates with the end of the member 33 to prevent the member 36 being displaced out of its bore by the pressure of fuel within the cavity and during an injection stroke.

During a filling stroke of the injection pump the member 36 is urged into contact with the ball 35 by the output pressure of the feed pump acting on its end remote from the head 37. However, the area of the ball which is exposed to the pressure of fuel within the groove 26 is such that the ball moves away from the seating to permit fuel to flow from the bore 29 to the injection pump. The force exerted by the member 36 is however sufiicient to close the ball 35 onto its seating very quickly after the shuttle 30 has contacted one of the stops. In this manner continued flow of fuel due to the inertia thereof into the injection pump is minimised so that the quantity of fuel flowing to the injection pump for subsequent delivery to the engine, is substantially equal to the theoretical quantity of fuel displaced by the shuttle 30.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A liquid fuel injectionpumping apparatus of the kind comprising in combination an injection pump which in use, is actuated in timed relationship with an associated engine and which during an injection stroke delivers fuel under pressure to an associated engine, a bore, a shuttle slidable in the bore, stops at the opposite ends of the bore to limit the excursion of the shuttle, means for feeding fuel to the injection pump, during successive filling strokes thereof from the opposite ends of the bore in turn by causing the displacement of the shuttle, a conduit leading to the injection pump and through which fuel flows from the bore containing the shuttle to the injection pump, a one way valve including a valve element and a seating, said valve element being displaced from said seating by the fuel flowing along said conduit to the injection pump and a fluid pressure operable member acting on the valve element in a direction to urge it onto the seating, the force applied by said member being suflicient to minimise the flow of fuel into the injection pump after the shuttle has contacted a stop.

2. A pumping apparatus as claimed in claim 1 in which said member comprises a piston one end of which is subjected to a fluid pressure and the other end of which acts upon the valve element, the area of said one end of the piston being so chosen in relation to the area of the valve element and the fluid pressures to which they are subjected, so that the valve element will be moved off its seating by the flow of fuel during movement of the shuttle.

3. A pumping apparatus as claimed in claim 2 including a body part, a distributor member rotatably mounted in the body part, said distributor member mounting the rotary part of the injection pump and incorporating a passage communicating with the injection pump, said conduit in part being formed in the distributor member and the one way valve being positioned therein.

4. A pumping apparatus as claimed in claim 3 in which the end of said part of the conduit remote from said passage terminates in a first circumferential groove on the periphery of the distributor member, the first circumferential grOOve having longitudinal grooves communieating therewith and which communicate in turn with the ends of the bore containing the shuttle. Y

5. A pumping apparatus as claimed in claim 4 in which said one end of the piston is open to a second circumferential groove on the periphery of the distributor member, said second circumferential groove communicating with a source of fuel under pressure, said distributor member having a third circumferential groove communicating with said source of fuel through the intermediary of an adjustable throttle, and the third circumferential groove communicating with longitudinal grooves communicating in turn with the ends of the bore containing the shuttle.

References Cited UNITED STATES PATENTS 2,950,681 8/1960 Walch et a1 417-462 2,989,003 6/1961 Evans 417462X 

